config.in

一套客户/服务器模式的备份系统代码,跨平台,支持linux,AIX, IRIX, FreeBSD, Digital Unix (OSF1), Solaris and HP-UX.

Configuration of AF's backup system
===================================

The parameters for the client side can be found in a 
file named 
@clientconf@ 
and for the server side in 
@serverconf@, 
that resides in the
directory @clientconfdir@ 
or @serverconfdir@,
respectively. Comments in those files are lines starting
with the pound symbol # as the first non-blank character.

These two files need not be edited by hand with an editor,
instead the programs @serverbindir@/afserverconfig [ configfile ]
and @clientbindir@/afclientconfig [ configfile ]
can be used. If you are 
running X, the programs are the same, but start with an 'x';
(Tcl/Tk must be installed): 
@serverbindir@/xafserverconfig [ configfile ]
and @clientbindir@/xafclientconfig [ configfile ] .
The parameters described below are the same for both versions.


Server configuration parameters
-------------------------------

 ServerIdentifier

  The identifier for the server. Default: The official hostname,
  followed by a colon and the full path to the configuration file.
  The server identifier can be used to become independent of the
  server machine name. This might be helpful, if the backup server
  should move to another machine. Whitespace characters may be
  used in this identifier, but they are replaced with asterisks *
  before comparing, so they are not significant


 Backup-Device

  This is the device the backup is written to. It can be any
  tape device with the capability to distinguish between several
  files on the media. It is mandatory to supply the no-rewind 
  device here, otherwise this package won't work properly. 

  Suitable device names for some OS-es:
  AIX:          /dev/rmt0.1
  Solaris:      /dev/rmt/0bn
  IRIX:         /dev/rmt/tps0d4nr
  HP-UX:        /dev/rmt/0hn
  Linux:        /dev/nst0
  Digital UNIX: /dev/nrmt0h
  FreeBSD:      /dev/nsa0

  If the drive has a media handler attached, a specifier for this
  may follow the device name. The format for this is
   =<drive-count>@<device>#<num-slots>^<num-loadbays> , for example
  =1@/dev/sg0#6^2 . Whitespace before and following the special
  characters = @ and # is allowed for readability. The example
  means: The drive is number 1 in the changer, /dev/sg0 is the
  changer device, that has 6 media slots and 2 loadbays. The
  parts =<drive-count> and ^<num-loadbays> are optional.
  If the server is only used for remote start and no real backup
  device should be accessed, a dash - should be configured here
  as device, so a respective warning to the server log will be
  suppressed


 Tape-Blocksize

  The blocksize of the tape device. This value specifies how many
  bytes are written to tape or read from it with one system call.
  Usually this value is at least 512 or a multiple of it.
  It is not very important if the blocksize is set to 2048
  or 1024. The main thing to keep in mind is that if there is a
  minimum, it should be respected (e.g. 1024 on AIX), otherwise
  media space is wasted.


 Tape-Buffer

  Three numbers and a filename can be given here. The first number
  is the desired size of the tape buffer in bytes. The optional
  second number is the high-watermark while writing in percent
  (default: 67), the optional third number is the low watermark,
  also in percent (default: 0). As long as the buffer fill rate
  does not reach the high watermark, nothing is written, but when
  it is reached, writing does not stop until the buffer fill rate
  is equal or below the low watermark. This procedure hopefully
  reduces tape wear and increases average writing speed, because
  excessive tape stops/starts are avoided. If the optional filename
  is given, buffering is done in the given file, which is mapped
  into the server's address space for that purpose. In the filename,
  patterns are replaced like with Changer-Configuration-File.


 Cartridge-Handler

  This value must be 1 or 0, which means, that you either have a
  cartridge handling system (i.e. some kind of robot) (1) or
  not (0). If you don't have a robot, you may nonetheless maintain
  a set of cartridges, that you will have to manually number. 
  The backup server side will inform you via email or console output,
  whenever another cartridge has to be inserted into the drive and what
  number it requires it is.


 Number Of Cartridges

  This number specifies, how many cartridges you are maintaining.
  If you have a cartridge handling system (some kind of robot),
  this is usually the number of cartridges, your system is juggling.


 Cartridge-Sets

  Several cartridge sets can be used. Here they can be specified.
  The specifiers for the cartridge sets must be separated by
  whitespace. Each specifier may consist of digits, commas and
  dashes. Examples for cartridge set specifiers: 1-5 7-9,12 6,10,11
  This example shows how to specify three cartridge sets. If the
  access to a cartridge set should be allowed only for certain
  clients, this may specified with a colon immediately following
  the set specifier without whitespace, followed by one of three
  forms: Either a list of hostnames, separated by commas and no
  whitespace inbetween, or the full path to a file containing the
  hostnames one per line, or by a command to be executed. The
  command must start with a bar | and must be enclosed in double
  quotes, if it is containing whitespace. If %H occurres in the
  command it will be replaced with the client name, who wants to
  gain access to the cartridge set. The command must exit with a
  status of 0, if access is to be granted, otherwise with an exit
  status unequal to 0. The name of the host to be checked is also
  written to standard input of this command, so %H needs not to
  be used. Examples specifying cartridge sets with restricted
  access:  1-5:apollo,localhost,taurus
           6-8,16:/usr/local/backup/etc/set2clients
           9-15:"| fgrep .my.domain.com"
  Remember, that grep will exit with 0, if a match has been found,
  otherwise 1. Note, that localhost and the network name of the
  machine should be both given, if the server is also a client.
  The names to be supplied here are not the client IDs configured
  on the client side, but the network names of the machines.
  If this parameter is not given, there is only the default set
  number 1 with all available cartridges, access is permitted to
  any client. Not all cartridges need to be included in a set and
  sets must not overlap.


 Max Bytes Per File

  The stream of data, that represents your backup, is divided into
  pieces (files on tape). This is done to find the files faster
  during a restore. This value determines, how large the pieces on
  tape may be in bytes. Some good values for a few tape technologies:

    QIC:              20000000
    DAT:              30000000
    Exabyte:          50000000
    DLT:             100000000


 Max Bytes Per Tape

  With this entry the number of bytes written to a single tape
  can be limited. Serveral entries with a leading range specifier
  allow to handle certain tapes differently. The range specifier
  must end in a colon : and may contain lists of ranges and numbers.
  A given number without a leading range specifier will be valid for
  all tapes not explicitly described. Default is use of full tape
  capacity. Several entries must be separated by whitespace and may
  look like the following examples:
    4000000000  1,3-5:3500000000  7,9-:5000000000
  This means: 3.5 GB for cartridges 1 and 3 through 5, 5 GB
  for cartridges 7 and 9 up to the last cartridge, 4 GB for the
  rest


 Full Append Mode

  Normally, when the insert (writing) position is forced to
  another tape with the cartis command or with the clientside
  option -G, the rest of the current tape remains unused. When
  this option is set to 1, it will nonetheless be used to write
  data on, if there is no free tape left


 Variable Append Mode

  In default mode, the place (tape and tapefile), where the next data
  will be written, is fix and can only manipulated using the command
  cartis or the clientside option -G. When the server wants to write
  with variable append mode enabled, any cartridge, that is in the
  drive, is belonging to the right cartridge set and is allowed to be
  written, will be accepted and appended to. Note, that this will also
  override the settings of cartis or option -G.


 Reject Unlabeled Tapes

  Default is to accept an unlabeled tape as the requested one and
  to label it automatically. If this behaviour is unwanted and only
  tapes with a recognized label should be permitted for writing,
  this parameter should be set.


 PreferCartInChanger

  When a tape gets full and another one must be chosen to continue
  writing, the server does not make a difference, whether a tape
  is available in a changer or not, if this flag is not set. This
  is the default. If this parameter is set, the next cartridge is
  chosen from those, that are available in the slots of a changer,
  if present and configured. If there is no tape found inside the
  changer, that is allowed to be overwritten, manual administrator
  interaction is nonetheless required.


 Cart-Insert-Gracetime

  This is the time in seconds, the program waits after another
  cartridge has been put into the drive. Normal devices need a
  certain time span to mount the tape to get it ready for use.
  Normally this value is not critical. If you estimate it too
  low, the ioctl-system-call will wait until the device becomes 
  available. This time is sometimes longer than two minutes,
  so if you want to proceed quickly after a cartridge
  change, you may measure the maximum time your system needs.
  Some tried values for a few tape technologies:

    QIC:         20
    DAT:         30
    Exabyte:     70
    DLT:         70


 Device-Unavailable-Send-Mail-After-Min

  If the streaming device is not accessible (i.e. an open or a
  tape handling command fails) or another backup server process
  is still running, the server process re-tries his attempts
  regularly. If it fails longer than the time in minutes
  supplied here, an e-mail is sent to the configured user in
  charge (see: User To Inform). Supplying 0 means: never send mail.


 Device-Unavailable-Give-Up-After-Min

  Same as Device-Unavailable-Send-Mail-After-Min, but this time
  not an e-mail is sent, but the server process exits silently
  leaving a warning in the log file. Supplying 0 means: try
  forever, never exit.


 Device-Probe Interval

  This is the interval in seconds, after that regularly the device
  is probed to be ready for reading. Thus after having ejected a
  cartridge it is automatically recognized, if a new cartridge has
  been inserted. For other media (e.g. exchangeable disks) this may
  not be suitable. Supply a 0 in these cases for no probing.


 SetFile-Command

  This is the (shell-) command to run to position the tape to a
  certain file. Usually this is something like a combination
  of:  mt -f <device> rewind  and  mt -f <device> fsf <number>.
  If the command you are supplying here starts to count with
  1 for the first file on tape, you should insert %n for the
  <number>. If it starts with 0, replace <number> with %m. If
  you don't want to type the devicename again here, you may
  write %d instead. For more pattern replacements see: Status-file


 SkipFile-Command

  This is the (shell-) command to run to skip over to a file
  later on tape. Usually this is something like
   mt -f <device> fsf <number>
  Insert %n, where the number of files to skip over must be
  supplied in the command, in the example instead of <number>,
  and %d, where the device should appear (here: <device>).
  For more pattern replacements see: Status-file


 Setcart-Command

  This is the (shell-) command to run to put a certain
  cartridge into the device. If the command you are supplying
  here starts to count with 1 for the first cartridge, you
  should insert %n in the place, where the cartridge number
  must appear. If it starts with 0, replace it with %m. If
  you don't want to type the devicename again here, you may
  write %d instead. If you don't have a command to perform
  this task, don't supply anything here. In this case you must
  set your cartridge handling system to sequential mode
  (automatically putting the next cartridge in, when the
  current one is ejected).
  For pattern replacements see: Status-file
  

 Changecart-Command